Free Steroid Conversion Calculator

Understanding Corticosteroid Equivalency

Corticosteroids are a class of steroid hormones—both naturally produced by the adrenal glands and synthetically manufactured—that share potent anti‑inflammatory, anti‑allergic, and immunosuppressive properties. They are used to treat a wide spectrum of conditions, from autoimmune disorders to severe allergic reactions. Although different corticosteroids have overlapping therapeutic actions, they differ markedly in anti‑inflammatory potency and duration of action. Because of these differences, switching from one corticosteroid to another requires careful dose adjustment to maintain the same clinical effect. The Steroid Conversion Calculator (also known as a Corticosteroid Conversion Calculator or Steroid Dose Calculator) is designed to assist healthcare professionals in performing such conversions quickly and accurately—whether for a simple prednisone conversion or for determining a dexamethasone equivalent dose.

Important: This tool is intended for medical professionals. The calculated conversions apply only to oral and intravenous administration. Patients must not change their therapy without consulting a physician.

Why Corticosteroid Conversion Is Needed

In clinical practice, it is often necessary to replace one corticosteroid with another. Reasons include differences in cost, drug availability, adverse effect profiles, or the need to adjust the duration of action. Because each corticosteroid has a unique potency relative to a reference (usually hydrocortisone), a direct milligram‑for‑milligram substitution would result in under‑ or over‑dosing. Conversion based on equipotency ensures that the patient receives an equivalent anti‑inflammatory effect.

Standard Conversion Table

The most widely accepted conversion factors are derived from the anti‑inflammatory potency data published by the National Adrenal Diseases Foundation. The table below lists the equivalent dose (the amount that provides the same anti‑inflammatory effect as 20 mg of hydrocortisone), the corresponding potency, and the typical duration of action for the commonly used corticosteroids.

Corticosteroid	Equivalent Dose (mg)	Anti‑inflammatory Potency	Duration of Action
Hydrocortisone	20	1	8–12 h
Cortisone	25	0.8	8–12 h
Prednisone	5	4	12–36 h
Prednisolone	5	4	12–36 h
Triamcinolone	4	5	12–36 h
Methylprednisolone	4	5	12–36 h
Dexamethasone	0.75	30	36–54 h
Betamethasone	0.6	30	36–54 h

Note: Potency values are relative to hydrocortisone = 1. The equivalent dose is the amount needed to achieve the same anti‑inflammatory effect as 20 mg of hydrocortisone.

How to Perform a Steroid Dose Conversion

The core principle is to keep the total anti‑inflammatory effect unchanged. This can be done using a simple proportion formula:

$$\text{Dose}_{\text{new}} = \text{Dose}_{\text{current}} \times \frac{\text{Potency}_{\text{current}}}{\text{Potency}_{\text{new}}}$$

Alternatively, a two‑step method can be used:

1. Convert the current dose to a hydrocortisone‑equivalent dose: $$\text{Hydrocortisone equivalent} = \text{Dose}_{\text{current}} \times \text{Potency}_{\text{current}}$$
2. Convert the hydrocortisone‑equivalent dose to the desired drug: $$\text{Dose}_{\text{new}} = \frac{\text{Hydrocortisone equivalent}}{\text{Potency}_{\text{new}}}$$

Both methods yield the same result.

Worked Example 1: Prednisone to Methylprednisolone

A patient currently takes 20 mg of prednisone. The goal is to switch to methylprednisolone (e.g., Solu‑Medrol). From the table:

• Prednisone potency = 4
• Methylprednisolone potency = 5

Applying the formula:

$$\text{Dose methylprednisolone} = 20\ \text{mg} \times \frac{4}{5} = 16\ \text{mg}$$

Thus, 20 mg of prednisone is equivalent to 16 mg of methylprednisolone.

Worked Example 2: Prednisone to Dexamethasone

Now convert 10 mg of prednisone to dexamethasone:

• Prednisone potency = 4
• Dexamethasone potency = 30

$$\text{Dose dexamethasone} = 10\ \text{mg} \times \frac{4}{30} \approx 1.33\ \text{mg}$$

Because dexamethasone has a much longer half‑life, the dosing interval will be longer (often once daily) compared with prednisone.

Adjusting Dosing Frequency

When switching between corticosteroids, it is essential to consider the duration of action (or half‑life). Shorter‑acting drugs such as hydrocortisone or cortisone require multiple daily doses, while longer‑acting agents like dexamethasone or betamethasone can be given once daily or even less frequently. As a rule:

• If converting to a drug with a shorter half‑life, increase the dosing frequency to maintain therapeutic effect.
• If converting to a drug with a longer half‑life, decrease the dosing frequency to avoid accumulation and adverse effects.

Always verify the typical dosing schedule of the target drug before making changes.

Clinical Considerations and Limitations

• Individualization: The calculated dose is an estimate. Factors such as the patient’s age, weight, severity of illness, concomitant medications, and hepatic or renal function may require adjustments.
• Route of Administration: The equivalences in the table are validated for oral and intravenous use. Other routes (e.g., intramuscular, topical, inhaled) have different bioavailability and should be converted using specific guidelines.
• Monitoring: After a switch, monitor the patient for signs of under‑ or over‑treatment (e.g., adrenal insufficiency or Cushing’s syndrome) and adjust accordingly.
• Related Analogy: The concept of potency‑based conversion is also used for other drug classes, such as opioids, where equipotent tables help clinicians switch between different analgesics. The present calculator, however, focuses exclusively on corticosteroids.
• Disclaimer: This calculator provides approximate equivalencies based on standard conversion tables. It does not replace professional medical judgment. Always consult current evidence and a qualified healthcare provider when managing corticosteroid therapy.